Does an A7105 with PA use power when not used?

The battery life on my Devo 7e has shortened a lot... I changed builds many times, and I changed the module used

I used to have a A7105 module without PA for my Hubsan X4, and that was working well indoor. I replaced that with a A7105 module with PA (full range), just in case.

Now, even if I never use the X4 model and I only use the built-in module for DSM receivers (i.e. I assume the A7105 is never powered), my battery life has decreased a lot. Granted, it might be something else decreasing battery life, and I need to look into better troubleshooting steps.

Does anyone know if the A7105 module with PA uses power even when not active? I will open up my Tx again and do some measurement soon, but I wonder if anyone here has pointers/suggestions that won't require reopening it

If I open it, I think I'll also add a switch that cuts power to the module when I don't need it, if I measure any non-trivial power usage

The PA and LNA ( if present ) (or board?) uses Power on some modules even when chip enable is off i have messured it for the XL7105. So yes simly having the module uses power.

EDIT: also deviation did not turn modules off properly upon changing protokoll, there was some work done to fix that, i dont if its done yet.

I also find the Devo 10 use power very fast so I change to Li-po battery
In the Devo 7e use 2S fully charged voltage will be 8.4v so I open and cut the red positive line in the back of the control unit connect two 1N4001 diodes in line(serial)to lower the voltage to prevent fry the MCU
I use 3S which is about 12.6v when full so I use one diode in the Devo 10
Li-po need to be taken out to balance charge but it last longer.
Use cheap low C type Li-po is fine

ZOOCOCO wrote: I also find the Devo 10 use power very fast so I change to Li-po battery
In the Devo 7e use 2S fully charged voltage will be 8.4v so I open and cut the red positive line in the back of the control unit connect two 1N4001 diodes in line(serial)to lower the voltage to prevent fry the MCU

you are taking some risk... 1n4001 diodes have a ~0.7V forward voltage drop, so you are feeding the 7e 7V at full charge, vs the usually 6V it's expecting.

Personally I prefer to use 2400mAh low self discharge NiMH batteries. Their voltage is a bit lower, but at 2400 mAh they have plenty of power to keep the 7e go for a long time. And they can be recharged directly without even removing them from the receiver. Cheap, too

robca wrote:

ZOOCOCO wrote: I also find the Devo 10 use power very fast so I change to Li-po battery
In the Devo 7e use 2S fully charged voltage will be 8.4v so I open and cut the red positive line in the back of the control unit connect two 1N4001 diodes in line(serial)to lower the voltage to prevent fry the MCU

Personally I prefer to use 2400mAh low self discharge NiMH batteries. Their voltage is a bit lower, but at 2400 mAh they have plenty of power to keep the 7e go for a long time. And they can be recharged directly without even removing them from the receiver. Cheap, too

How ?

The 7e has a built-in battery charger, there is a port in the back accepting 8-12V, with the usual 5.5x2.1mm jack

robca wrote: The 7e has a built-in battery charger, there is a port in the back accepting 8-12V, with the usual 5.5x2.1mm jack

The same as for PPM output ?

No, it's on the other side of the TX from the trainer port:


I use it to charge NiMH batteries in mine as well. I don't know if it's a "smart" charger or not, so I mostly use it for short periods of time to top off the batteries. I use a standalone charger to properly charge them

Shocking isn't it?I did plug it 8.4v straight and had it for a while but I decided to add 2 diodes to drop the voltage just to play safe.
Maybe I should add one more diode to make it 3 or even 4 ?

NiMH is good to use ofcause
My NiMH is somehow a little bit too fat I try it and I battle to get it out but they are not that cheap compare to low C rate Li-po.

My NiMH is somehow a little bit too fat

I have some cheap NiMH that are like that as well. The Eneloop ones I recently bought fit in much nicer, but they are more expensive. I've thought about going the LiPo or LiFe route, but haven't found one that I can be sure will fit.

My Li-po pack is brought via internet shopping which is build to fit but as I mention it before It will be 8.4v when fully charge which made me uneasy thinking maybe one day the Mcu will be cooked so I decided to drop the voltage
Check the internet shopping or you have to join those NiMH by thin plates make a pack without using the battery case
Or you need to join 4 diodes to drop it to 6v

ZOOCOCO wrote: My Li-po pack is brought via internet shopping which is build to fit but as I mention it before It will be 8.4v when fully charge which made me uneasy thinking maybe one day the Mcu will be cooked so I decided to drop the voltage
Check the internet shopping or you have to join those NiMH by thin plates make a pack without using the battery case
Or you need to join 4 diodes to drop it to 6v

From what I recall, Walkera themselves offered a LiPo pack for the Devo7e and Devo6s. It was just an 800 mah 2s lipo pack that was overpriced (in my opinion). I don't have the original link handy but I can't see how you can harm the radio by using any LiPo that you can manage to fit into the 7e if they are standard 2s wired. A lot of the initial charge is lost when it goes through the voltage regulator so I found that they didn't last a very long time (the 800mah ones that is).

There is also a mention of making a 3s liPo pack into a 2s for use in the Devo7e. It was a much larger mah rated pack and I didn't hear of any problems with that either.

Shanman3us

This my story:
I went to my local hobby shop where I brought my heli from and complain about power consumption and they suggested using li-po and give me a li-po pack with plugs already and they say it will fit which is 2200mah for around $10(usd)
I even find 3s for my devo 10 from internet for under $10 which is about the same price for 4 NIMH
So I plug it in after charge nothing bad or smoke happen but the other day a guy told me that I should add diodes to drop voltage just to stay on the safe side because on the back of the control unit there is small white print said "only use NIMH or NICD etc......."
I think that is for charging from that hole only.
Li-po hold voltage better charge faster cheaper if you compare to 8 NIMH and no memory effect (no need to cycle the battery)just don't over charge it always keep it around 80% full or 4v per cell if you not going to use it for long or discharge it to storage voltage

www.ebay.com/itm/11-1V-2200mAh-Li-poly-L...&hash=item23360f8740

Here is one that I find so look hard and you will find it cheap
perhaps you can take out 1 cell and change plugs to make it 2S

www.ebay.com/itm/Venom-5C-2S-2400mAh-7-4...&hash=item5d495bc419